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CONTROL AND PREVENTION OF CONTROL AND PREVENTION OF EMERGING ZOONOSES.EMERGING ZOONOSES.
Bruno B. CHOMEL Bruno B. CHOMEL DVM,PhD
WHO/PAHO Collaborating CenterOn New and Emerging Zoonoses
Department of Population Health and Reproduction School of Veterinary Medicine, University of California
Davis
AAVMC: Agenda for Action: Veterinary Medicine’s AAVMC: Agenda for Action: Veterinary Medicine’s Role in Biodefense and Public HealthRole in Biodefense and Public Health
Washington, DC. November 1Washington, DC. November 1-- 3, 20023, 2002
Emerging Infections
"New, reemerging or drug-resistant infections whose incidence in humans has increased within the past two decades or whose incidence threatens to increase in the near future."
Emerging Infections: Microbial Threats to Health in the United States. Institute of Medicine, 1992.
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Emerging and ReEmerging and Re--emerging Zoonosesemerging Zoonoses
• Zoonoses: “The diseases and infections which are naturally transmitted between vertebrate animals and man.” (WHO, 1959)
•Emerging and re-emerging zoonoses: “ Zoonotic diseases caused either by totally new or partially new agents, or by micro-organisms previously known, but now occurring in places or in species where the disease was previously unknown.” (Meslin, WHO, 1992)
ZOONOSES and the RISK of DISEASE EMERGENCEZOONOSES and the RISK of DISEASE EMERGENCETaylor, L.H. and Woolhouse, M.E.J., U. of Edinburg, U.K.
Int. Conf. Emerg. Infect. Diseases, Altanta, GA, USA, July16-19, 2000
InfectiousInfectious Human Human ZoonosesZoonoses EmergingEmergingOrganismsOrganisms PathogensPathogens PathogensPathogens
(N=1709) (N=832) (N=156)Viruses/Viruses/PrionsPrions 507 (30%) 183 (22%) 64 (41%)Bacteria/Bacteria/RickettsiaRickettsia 541 (32%) 250 (30%) 48 (31%)FungiFungi 309 (18%) 83 (10%) 16 (10%)HelminthsHelminths 286 (17%) 275 (33%) 9 ( 6%)ProtozoaProtozoa 66 ( 3%) 41 ( 5%) 19 (12%)
49% of the human pathogens are zoonotic and 9% are emerging pathogens. 73% (114/156) of the emerging pathogens73% (114/156) of the emerging pathogens arearezoonoticzoonotic. Overall, . Overall, zoonoticzoonotic pathogens are pathogens are more than 3 times more than 3 times more likelymore likely to be associated with emerging diseases than nonto be associated with emerging diseases than non--zoonoticzoonotic pathogens.pathogens.
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ZOONOSES and the RISK of DISEASE ZOONOSES and the RISK of DISEASE EMERGENCEEMERGENCE
Taylor, L.H. and Woolhouse, M.E.J., U. of Edinburg, U.K.Int. Conf. Emerging Infectious Diseases, Altanta, GA, July 16-19, 2000
• 49% (832) of the 1,709 human pathogens are zoonotic and 9% (156) are emerging pathogens, but 73% (114/156) of the emerging pathogens arezoonotic. • Overall, zoonotic pathogens are more than 3 times more likely to be associated with emerging diseases than non-zoonotic pathogens..
•• All but one of classified category A biological agents for bioterrorism and most of category B are zoonoses.
Emerging Zoonoses• Some Major Bacterial Etiologic Agents of New Zoonoses Identified Since 1976
• 1976 Capnocytophaga canimorsus• 1977 Campylobacter spp.• 1982 E. coli O157:H7• 1982 Borrelia burgdorferi (Lyme disease)• 1983 Helicobacter pylori and other spp.• 1986 Ehrlichia chaffeensis (HME)• 1992 Bartonella henselae (Cat scratch Disease)• 1994 Rickettsia felis (Murine typhus like)• 1994 E. Equi/A. phagocytophila (HGE)
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Emerging Zoonoses• Some Major Viral Etiologic Agents of New Zoonoses Identified Since 1990
• 1991 Guanarito virus (Venezuelan hemor. fever)• 1993 Sin nombre virus (Hantavirus Pulm.Syndr.)• 1994 Sabia virus (Brazilian hemorrhagic fever)• 1994 Hendra virus (Equine morbillivirus)• 1996 Australian bat Lyssavirus (Rhabdovirus)• 1997 Menangle virus (paramyxovirus)• 1997 Influenza virus H5N1 (Hong Kong)• 1998 Nipah virus (Paramyxovirus)• 1999 Influenza virus H9N2 (Hong Kong)
Emerging Infectious Diseases• Major Factors Contributing to theEmergence of Infectious Diseases
• Human demographics and behavior• Technology and Industry• Economic Development and Land Use• International Travel and Commerce• Microbial Adaptation and Change• Breakdown of Public Health Measures
Institute of Medicine Report, 1992• Bioterrorism
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Wor
ld P
opul
atio
n in
bill
ions
(
)
Day
s to
Circ
umna
viga
te (
)
th
e G
lobe
Year1850
0
400
350
300
250
200
150
100
50
2000
0
1900 1950
1
2
3
4
5
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Speed of Global Travel in Relation toWorld Population Growth
From: Murphy and Nathanson. Semin. Virol. 5, 87, 1994
0
10
20
30
40
50
60
70
80
1790
1800
1810
1820
1830
1840
1850
1860
1870
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Year
Popu
latio
n / s
quar
e m
ile
Population Density, United States, 1790Population Density, United States, 1790--20002000
3.9m3.9m
281m281m
Source: F.A. Murphy, UCD
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Emerging Zoonoses• Estimated Global Mobile Population
• International Travelers 698 million (WTO, 2000)
• Migrant Workers 70-80 million (ILO, 2001)
• Refugees/Uprooted People 22 million (UNHCR, 2002)
• Undocumented Migrants 10-15 million (ILO, 2000)
• Migrant Victims 0.7 million (IOM, 2001)of Trafficking
Emerging Infections: Technology and Industry
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Emerging ZoonosesFood-Related Illness and Death
in the United States(Mead et al., EID, 1999)
It is estimated that annually food borne diseases cause approximately:
• 76 million illnesses
• 325,000 hospitalizations
• 5,000 deaths.
Emerging ZoonosesChanges in the Factors that Contribute to the Epidemiology of Food-borne Diseases
(Osterholm, 2002)
• Diet• Commercial food service• New methods of food production• New or re-emerging infectious agents• Ethnic preferences• “High-risk” populations, especially increase of immuno-compromised individuals (up to 20%)
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Emerging ZoonosesFactors Associated with the “Globalization”
of Food-borne Diseases(Osterholm, 2002)
• Water• Animal feeds and manures• Workers • Transportation• Rodents, other wildlife, insects• Food processing
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Emerging Infections: Economic Development and Land Use
Raccoon Rabies, United States,
1977-1999(Source: F.A. Murphy,
UCD)
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Black flying fox
Fruit bat (Pteropus alecto)Range: North to Papua New Guinea and eastern islands of Indonesia; South to New South Wales.
In 1996, this species and another the little red flying fox (P. scapulatus), were shown to carry a virus very closely related to rabies virus. Since then, flying foxes were also shown to carry the newly discovered Hendra and Nipah viruses.
(Source: F.A. Murphy, UCD)
NipahNipah virus, Malaysia, 1998virus, Malaysia, 1998
Deforestation, urbanization, increased pig production….
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EMERGING, REEMERGING, RE--EMERGING ZOONOSESEMERGING ZOONOSES
LeptospirosisLeptospirosis
In the past: mainly serovars: L. canicola, L.
icterohaemorrhagiaeIncreased cases in dogs in USA in recent years,in California: L. pomona, L. bratislavaIn Massachusetts, New Jersey, New York, Michigan:L. grippothyphosa, L. pomona, L autumnalis
Clinical changes: acute renal failure rather than hepatic insufficiency or coagulation
Emerging ZoonosesNew and Exotic Pets, Hunting Pens and Game
Translocation• Translocation of infected animals:
• bats and rabies • brucellosis and reindeer • echinococcosis and foxes
• Translocation of susceptible animals: • ostriches and emus and Western Equine Encephalitis
• Hunting pens: rabies and raccoons
• New and exotic pets: • salmonellosis and iguanas, African pygmy hedgehogs• Egyptian bats and rabies
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Number of Salmonella Marina Isolates Reported Anually and Number of Iguanas Imported Annually
0
10
20
30
40
50
60
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
Year
No.
S. M
arin
a is
olat
es
0
200000
400000
600000
800000
1000000
No.
igua
nas
impo
rted
No. of S. Marina isolates
No. of iguanas imported
Pediatrics 1997;99:399-402.
Emerging ZoonosesEmerging Bacterial Zoonoses and the
Immunocompromised Individuals.
• Salmonellosis, Campylobacteriosis
• Rhodococcus equi, Bordetella bronchiseptica
• Bacillary angiomatosis (Bartonella henselae, B. quintana)
• Fish tank Granuloma (Mycobacterium marinum)
• Dog bites (Capnocytophaga canimorsus)
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Emerging Zoonoses: Why Now?
• Better tools for diagnosis of fastidious organisms: The Molecular Microbiology Revolution: Hantavirus, Bartonella, etc…
• Epidemiological studies, outbreak investigation• Surveillance systems: Hantavirus, influenza,
leptospirosis, Hendra and Nipah viruses.• Wildlife studies have revealed new pathogens;
new studies done on interaction between wildlife reservoir and domestic animals/humans
• Increased interest in vector borne diseases i.e., tick-borne infections: Ehrlichioses, Lyme, etc.
Emerging Zoonoses
• Knowing is not enough; we must apply.• Willing is not enough; we must do.
(Goethe)
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Emerging Zoonoses: Control and Prevention
• Recognition • Investigation• Collaboration: Interagency structures • Advanced structures for diagnosis &
surveillance • International & interdisciplinary interventions• Applied epidemiological and ecological
research: Field-trained specialists: Epidemic Intelligence Veterinary Public Health Officers
• Education: Training, technology transfer• Information/Communication
Emerging Zoonoses: Control and Prevention
• Recognition: Emerging zoonotic infections first needto be identified.
Traditional approach: identification of a human health problem leading to identification of problems in domestic or wild animal populations (i.e. Rift Valley fever, Q fever, chlamydiosis).New approaches: identification of a health problem in
animals that could be associated with human disease (West Nile virus, USA, 1999).
investigation of potential pathogens in wildlife leading to identification of new reservoirs: Lyssavirus in bats, Australia, Brucella spp. in marine mammals.
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Emerging Zoonoses: Control and Prevention
• InvestigationCollaborative field work of multidisciplinary teams
with the support of expert staff scientists and advanced laboratories with molecular biological and immunological technologies.
“Shoe-leather” epidemiology initially to determine main risk factors and potential reservoirs, leading to preventive measures: Hantavirus, Americas, Nipah virus, Malaysia.New approach: Inventory of pathogens carried by various wildlife species, especially when encroached with human habitat: opossums reservoirs of Rickettsia felis, murine typhus, sarcocystis neurona.
Emerging Zoonoses: Control and Prevention
• Collaboration: Interagency Structures
• Need for a scientific bridge between various disciplines: zoology, ecology, ornithology, geography, veterinary and human medicines…as illustrated by the early “West Nile fiasco” bird disease? or human disease?…Which agency is in charge?
• Interface between Public Health and Veterinary Public Health at local, national and international levels.
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Emerging Zoonoses: Control and Prevention
• Advanced structures for diagnosis and surveillance,international and interdisciplinary interventions:
Know-How, availability and flexibility
• Applied epidemiological and ecological research: Field-trained specialists: Epidemic Intelligence Veterinary Public Health Officers
Fellowships, training grants, PhDs
• Develop training in molecular epidemiology: The microchip revolution: on site instantaneous
multitests
Emerging Zoonoses: Control and Prevention
• Education:Training, technology transfer.• Information/Communication
– Enhance communication of information
– Use diverse communications methods
– Establish partnerships to ensure rapid implementation of prevention measures
– An on-line journal for new and emerging disease information
(Source: F.A. Murphy, UCD)
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Control and Prevention of Emerging Zoonoses:
CONCLUSIONS
• Discovery-to-control continuum: discovery/recognition, epidemiologic field investigation, etiologic investigation diagnostics development, focused research, technology transfer, training and outreach, prevention, control and elimination, if possible.
• What made it possible? Better diagnosis tools, awareness (especially of the wide wildlife reservoir), readiness, establishing surveillance systems, collaboration and technology transfer.
• What should be next? Increased awareness and improved curriculum in VPH/ Zoonoses for DVM students. Develop a group of field-trained specialists.
Strategies in Prevention and Control:What we need (G.A. Gellert, Nature, 1994;370:409)
• A rapid communication system• A wide-ranging legal authority• A way to get full participation of everyone involved
and to deal with “turf battles” (who gets the credit?) • A coordinated response to the media and a
professional response to public misperceptions• A progressively redefined case definition (for clinical
and epidemiological purposes)• A locally updated clinical management guidelines• A locally updated biosafety management guidelines• Reagents and diagnostic technology transfer to local
sites• A way to shift from emergency to regular response
mode.